Internal combustion engine manifold heater



Feb. 10, 1959 LE ROY/E. CLARK 2,

gNTERNAL COMBUSTION ENGINE MANIFOLD EATER Filed Oct. 4, 1957 INVENTOR. 45 Pay 5. CLERK United States Patent INTERNAL COMBUSTION ENGINE MANIFOLD HEATER Le Roy E. Clark, Racine, Wis.

Application October 4, 1957, Serial No. 688,187

4 Claims. (Cl. 219-38) ample, so as to cause the wire to glow and thus heat the air just prior to its entry into the cylinders.

These heating devices comprise a body that is threaded into the manifold, said body having a stem insulatingly passing therethrough which extends well into the interior of the manifold. The heating coil is wound around the stem and is spaced radially therefrom. The coil is usually coextensive in length with the stem and is welded at its inner end to the inner end of the stem. The outer end of the coil is Welded to the body. Electricity is passed from the source through the stem, coil and body where it is grounded in the frame of the engine.

These heaters, or glow plugs," being mounted directly on the engine are subjected to a considerable amount of vibration for long periods of time, in fact whenever the engine is operating.

Prior art heaters of this type have met with reasonable success. However, the life of such heaters has been rather limited due to breaking of the coil after a period of use. More particularly, the strain on the wire usually causes it to break adjacent the point where it is welded to the body.

In accordance with the present invention, an electric heater for a manifold of an internal combustion engine has been provided which has much longer life and in which breakage of the coil has been substantially eliminated.

More particularly, a heater of the above type has been provided in which the outer end of the Wire coil is fastened to the body of the heater in such a way that this end of the coil is not subjected to repeated bending forces.

These and other objects and advantages will appear hereinafter as this disclosure progresses, reference being had to the accompanying drawings, in which:

Figure. 1 is a fragmentary, side elevatio-nal view of an internal combustion engine having an inlet manifold with a heater therein;

Figure 2 is an enlarged perspective view of a heater made in accordance with the invention;

Figure 3 is a side view of the heater shown in Figure 2, partially in section;

Figure 4 is a fragmentary perspective view of a modified connection between the inner ends of the wire coil and stem; and

Figure 5 is a fragmentary view, with parts broken aw-y and in section, of a modified form of connection between the outer end of the wire coil and the body of the heater.

Referring in greater detail to the drawings, the internal combustion engine 5 has an intake manifold 6 secured thereto through which the air is drawn for combustion ygzpnrposes. The electric heater 8 has a body 9 including a threaded portion 10 engaged in the outer wall of the manifold. The body also includes a nut portion 11 by means of which it is inserted in or removed from the body. In the embodiment of the invention shown in Figures 2 and 3, the inner end of the body terminates in a reduced diameter portion in the form of hub 12 which is located within the manifold and a radial shoulder 13 is located between the hub and threaded portion.

A bore 14 extends through the body 9 and a sleeve 15 of insulating material is inserted in the bore. This sleeve may be made of rubber or may be formed by pouring porcelain between the stern and body. A stem 16 passes through the sleeve 15 and extends a considerable distance into the manifold. The stem is formed of two different diameters providing a shoulder 17 against which bears the metal washer 18.

Insulating washers 19 and 20 are located on the inner and outer sides of the body 9 so as to complete the electrical insulation of the stem 16 from the body. A nut 22 is threaded on the outer end of the stem to rigidly secure the body to the stem.

A positive wire 23 is attached to the stern and held in electrical contact therewith by the lockwasher 24 and nut 25. The hot wire 23 is connected to a source of energy, such as a battery carried by the vehicle on which the engine is mounted.

The heating coil 27 is formed from a high resistance Nichrome wire which is slipped over the stem and spaced a radial distance from it. The coil extends from the body to the inner end of the stern where the inner end of the wire extends through a radial slot 28 in the end of the stem. As shown in Figure 4, the ends of the stem itself may then be peened or pinched over so as to form a staked joint holding the wire captive therein. Other suitable means may be employed to secure the wire as by the welding shown in Figs. 2 and 3.

One form for securing the outer end of the coil to the body has been shown in Figures 2 and 3, wherein the inner end of the coil 27 is slipped over the hub 12 which is of such a diameter so as to snugly receive the coil thereon. It will be noted that there are no abrupt bends in this end of the wire coil, but, instead, an end portion of the coil itself is securely welded to the hub.

Thus the wire is attached tangentially to the periphery of the hub and extends smoothly from its contact with the body into the free part of the coil proper. The wire extends from the body in a direction which is non-axial to the heater. Other ways of securing this outer end of the coil to the body may be employed and still come within the scope of this invention. For example, a hole 29 may be drilled in the body in a non-axial direction and the end 30 of the coil inserted and a staked joint formed here too, as by deforming the aperture. In any case, however, it is important that the wire leave the body in a non-axial direction in respect to the axis of the heater.

The stem and coil extend for a considerable distance into the manifold, thus forming an overhanging mass supported only at the outer end, that is, on the body of the heater.

In operation the electrical energy passes through the coil and is grounded through the body 9 by the engine and frame of the vehicle. The high resistance coil glows red with heat thus heating the incoming air to aid starting of the engine.

During operation, this heater is subjected to the many and various vibrations that emanate from an internalcombustion engine. Being mounted rigidly to the engine, these vibratory forces are transmitted directly to the heater. These forces are magnified in the overhanging 3 I mass of the heater and cause the coil and stem to have considerable. movement.

In prior art devices, the coil usually had an outer end portion that was bent so as to be in substantial axial alignment with the'heater and this axially extending portion, was then welded in a corresponding-axial bore-in the body. The repeated flexing action due to the vibrations, particularly of the coil, has resulted in eventual breaking of the coil adjacent to its point of connection to the body. In-other words, this failure occurred in the'axial portion adjacent the body Where the flexing was concentrated and especially violent at certain frequencies.

With the device of the present invention, marked in crease in the life of the heater has resulted, even under the most severe conditions. In fact, in actual practice breakage of the coil has been-substantially eliminated.

With the coil secured to the body in accordance with this invention, any forces due to whipping or flexing 'of the coil are absorbed axially along the length of the wire and by slight torsional movement of the spring coil itself. Any localized area of fatigue in the coil has been eliminated and these strains are now more evenly distributed through the coil windings.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I claim:

1. An electric heater for an internal-combustion engine manifold comprising, a body having means for connection to said manifold, a stem extending through said body and insulated therefrom and having a free end adapted to be in said manifold, a heating Wire wound around said stem and spaced therefrom and secured at one end to said stem free end, said wire at its other end wound around a portion of said body and secured thereto and extending from said body in a direction substantially normal to the axis of said heater.

2. An electric heater for an internal-combustion engine manifold comprising, a body having means for connection to said manifold, a stem extending through said body and insulated therefrom and having a free end adapted to be in said manifold, a wire heating coil spaced around said stern and secured at one end to said free end, said body having a cylindrical hub, said coil at its other end mounted around said hub and welded thereto.

3. Anelectric heater for an internal-combustion engine manifold comprising, a body having means for connection to said manifold, a stem insulatingly extending through said body and having a free end adapted to be in said manifold, a wire heating coil spaced around said stem and welded at one end to said free 'end,'said body having a cylindrical hub of'a diameter substantially the same as the coil internal diameter, the other end of said coil slipped over said hub and welded thereto.

4. An electric heater for an internal-combustion engine manifold comprising, a body having a threaded portion References Cited in the file of this patent UNITED STATES PATENTS 1,474,909 Medveczky Nov. 20, 1923 1,536,075 Connors May 25, 1925 1,570,413 Smith Ian. 19, 1926 2,139,777 Skok et al., Dec. 13, 1938 Balzer et al Oct. 4, 1955 

